airport sees signal but no internet

I am on a 900mhz iBook running 10.2.8.
My airport card seems to be having some issues, and I am having some problems with troubleshooting.
Starting Friday night, I noticed my internet blinking (via my airport wireless card). I checked the router, no problems with the router. Also, my roommate's wifi connection is running flawlessly, so it's not a router level problem.
I can connect fine via my ethernet port, so i don't think my ISP has mistakenly blocked me.
My airport settings are normal; cable modem, using dhcp, etc. The card can see my router and it's name, and shows full signal. But no internet comes in. Also, I cleared my router logs after resetting it and it did not show my computer under the connection logs.
Finally, I tried going into the airport utility and scanning for my router, which it found, and having it "join" my network. The first time it worked, but only for about 5 minutes, then the network blinked out again. Since then it hasn't worked.
I repaired permissions and ran the macjanitor scripts. I even rebooted!
Any other troubleshooting suggestions, or should I just bite the bullet and head over to my local apple store for a genius consult?

You know the same thing happened to me recently and I was just about to post about it. I used to be able to walk into the library here at school and connect to their wi-fi network with no problems. Now I have the exact same problem. I have a full signal, but I cannot get assigned an IP number from DHCP and therefore cannot connect to the internet. Does anyone know what's going on?

I am getting the same problem (i think). Basically i connect to the Belkin router fine, 90% of the time, and i have half bars of signal.
Half the time it gets the correct ip address and can connect and half of the time it gets a completely wrong ip address and says something like "airport is connected to the Belkin54g but no ip address has been assigned" or something along those lines and i can't connect to the internet. When i cycle through different network profiles (all set up to connect with dhcp) sometimes it gets the right ip address again after 2 mins and sometimes it doesn't in 30.
It is completely random, no interference due to cordless phones, had Airport card replaced and problem has persisted, had a ibook and that worked pretty much 99% of the time. Called Apple up very pissed off but received the "we can't do anything, you have to take it to a local reseller (that is about 30 miles away) and it leave it with them. I am not going too though, i doubt they would look after my imac, give it back with new faults and in about 2-3 weeks and i need my imac for work.

I have this problem too!
I get it when connecting to most open WiFi signals.. I can join, get full signal but no connection to the internet in any way.
Same happened when setting up my OWN WiFi... don't know how it worked eventually, just did.. i haven't touched any of the settings since just so i don't go through the night mare and DAYS it took me to get it to work in the first place.
Glad I'm not alone, hopefully apple will catch on and put out a fix.

Friggin annoying when your in a Cafe and all the Windows machines are joining the wifi and you stuck scratching your head with no success...

I've had this same trouble recently when I took my iBook with me to Atlanta.
The iBook was picking up the signal from the hotel, but i could not connect.
Finally, I talked to a representative who didn't help , and fixed it myself.
I shutdown the iBook, unplugged airport, replugged it back in, and turned it back on. I may have had to restart again I am not sure, but that fixed the prob.

it sounds simple, though it helped as mentioned before: diconnect the airportcard, and connect it again - and do not forget to put in the little cable! i forgot that once and had full signal, but no internet.
good luck folks!
.a

it looks like apple has a few discussion threads on this on their boards too...
maybe it's the age of the airport cards?
or maybe there's some new ibook problem! one we're all encountering simultaneously! w00t!

Simple answer: click taskbar icon, clck "Other...", and reconnect to your network manually, by entering the name and key. Works even when it believes it's already connected, it just needs a figurative kickin'.

Hey guys-I'm sitting in a cafe right now and everything's working fine. I don't understand why it happens in some places and not others. And it seems really random. Could it just be a signal problem? Oh-and I'm on an iBook G4 1 Ghz.

Simple answer: click taskbar icon, clck "Other...", and reconnect to your network manually, by entering the name and key. Works even when it believes it's already connected, it just needs a figurative kickin'.

Click to expand...

I can sit right in front of the router, do that, and nothing, Just tells me there was an error connecting to the network.

It's like it has a mind of it's own...and got tired of the internet. It takes breaks, and then connects itself again.

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